Implement Property based Testing

[MicahGale]

Property-based testing is a more exhaustive automated testing than traditional unit testing.

I found this tutorial, using the hypothesis framework.

[MicahGale]

Also need to look into mutation testing.

[MicahGale]

https://mutmut.readthedocs.io/en/latest/index.html

[MicahGale]

Initial mutation testing results are not promising:

🎉 Killed mutants.   The goal is for everything to end up in this bucket.
⏰ Timeout.          Test suite took 10 times as long as the baseline so were killed.
🤔 Suspicious.       Tests took a long time, but not long enough to be fatal.
🙁 Survived.         This means your tests need to be expanded.
🔇 Skipped.          Skipped.

1. Using cached time for baseline tests, to run baseline again delete the cache file

2. Checking mutants
⠧ 6770/6770  🎉 4726  ⏰ 9  🤔 1  🙁 2034  🔇 0

[MicahGale]

mutmut results
mutmut.txt

[MicahGale]

Update.

I have added hypothesis as a dependency. I have started using PBT in new tests as it makes sense. See the 1.0.0a1 development.

At some point we should go back and add PBT to a lot of the older tests.